1. Field of the Invention
The present invention generally relates to a motor and, more particularly, to a motor including a stator bobbin having a bearing abutting member that avoids a bearing and a rotor from disengaging from a shaft tube thereof.
2. Description of the Related Art
A conventional motor is shown in FIG. 1, and includes a housing 70, a rotor 80 and a stator 90. The housing 70 includes a hollow shaft tube 71 having a sealed bottom. A bearing 72, a retaining plate 73 and an oil end cap 74 are received in the shaft tube 71. The center of the rotor 80 includes a shaft 81 rotatably extending through the bearing 72. An annular groove 811 is formed on the shaft 81 and is close to the free end of the shaft 81. The inner edge of the retaining plate 73 extends into the annular groove 811. The stator 90 is mounted around the shaft tube 71 to drive the rotor 80 to rotate.
In general, for the conventional motor, the retaining plate 73 is partially received in the annular groove 811. Thus, the retaining plate 73 can prevent the rotor 80 and housing 70 from separating when the rotor 80 rotates, with said separation happening when the shaft 81 moves in a direction parallel to a longitudinal axis of the shaft tube 71. A part of the shaft 81 forming the annular groove 811 to receive the retaining plate 73 is defined as having a length “L” in a longitudinal direction, and the outer periphery of the shaft 81 in said part does not come into contact with the inner periphery of the bearing 72 when the rotor 80 rotates normally. Therefore, because of the length “L” of the part, the shaft 81 does not come into contact with the bearing 72. Thus, the contact area between the shaft 81 and the bearing 72 is reduced, causing low rotating stability of the rotor 81. Especially, for a micro-motor under the condition of limited contact area between the shaft 81 and the bearing 72, the low rotating stability of the rotor 81 is induced more easily.
Furthermore, in order to prevent the rotor 80 and housing 70 of the conventional motor from separating, the retaining plate 73 must be partially received in the annular groove 811. Therefore, in assembly, the combinations between the shaft 81 of the rotor 80, the bearing 72, the retaining plate 73 and other related components are completed in the shaft tube 71. Thus, it's difficult to check whether all the mentioned components are truly and stably coupled in the shaft tube 71. Consequently, assembling quality of the conventional motor is uncontrollable and operation for assembling said motor is inconvenient.